On Wed, 12 Jun 1996 12:20:20 +0100 
 saw@sun0.urz.uni-heidelberg.de (Hauke Fath) wrote:

 > is it possible to move the CPU to supervisor mode and/or access the
 > interrupt mask in reg 'SR' from userland code? If so, how?

Well, you can't really do that.  If I recall correctly, attempting to 
modify the SR from non-supervisor mode will cause a priviledge violation 
trap.  I think even _reading_ the SR will cause a trap in user mode.

 > I am trying polled data transfers on the SWIM and have to block all
 > interrupts while reading.

If that's the case, you really need a kernel device driver which provides 
the semantics you need.

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